Process for conversion of lower oxids of nitrogen to higher oxids of nitrogen.



F. SPARRE. PROCESS FOR CONVERSION OF LOWER OXIDE! 0F NITROGEN T0 HIGHBROXIDS 0F NITROGEN.

APPLIOATIO] FILED SEPT. 7, 1907. Y 1,008,383, Patented Nov. 14, 1911.

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to nitration.

' i STATES 'r grsmonmoliz PM; 01 WILMINGTON, DELAWARE, ASSIGHOB TO THE I. I. DU 20!! III meanest.

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Be. 'itknown that I, FIN Sum, a suli'ect of the King of Norway, residin at ilmington, county of Newcastle, an. State of .6 Delaware, hav e invented a new and useful Improvementin Processes for Conversion of Lower Oxids of Nitrogen to -Higher Qxids of Nitrogen, of which the followin is a full, clear, and exact description, re erence had to the accom an in drawin s m P y g 3 form a part of this specification. In the nitration of cellulose and glycerin, by, means of a mixture of nitric and sulfuric acid, there are produced lower oxids of nitro en, such for instance as N,O,, which are of ow value. These lower oxids an dissolved by the acid and for the larger part form nitros l-sulfuric acid, in which 7 case one-half of e lower oxid is converted into .nitric .acid, and the other half into nitrosylsulfuric acid which has no nitrating value. 'Thus at least one-half of the nitroin the lower oxids is in useless form.

f they could be cheaply and readily oxidized, so as to form nitric acid, they would at once become of the desired value. Usuall r the acids are used over and over again,

on bein strengthened up by the addition ofzome esh strong acid before each new In this way the percentage of lower oxids increases continuously and at some time they have to be removed. These oxids can be removed and in part oxidized by certain, special distillations. Such oper- 85 ation and asparatus, however, are rather expensive an a loss of fixed nitrogen takes lace. Furthermore "such recesses would ail in cases where the liquid to be. treated was a solution with lower oxids as a prin- 4 cipal com nent. I have discovered a new rocess w ereby these low oxids of nitrogen in solution may be converted into nitric S kin nerally the 'rocess b which tfi p y e result is to subject the lower oxids. of nitro n in solution to the action of oxy pr uced by an electric current. It woube impossible to produce the result by merely passing a currentof electricity Specification of Letters Patent.

Application filed September ,7, 1907. Serial No. 891,758.

vantage to have the Patented Nov. 14, 1011.

in solution for the reason that while. oxg'gin would be produced at one electrode I source of current supply, h drogen would be produced at the other e ectrode of the source of current suppl and the actions of these two would neutra ize each other, causmg the oxids of nitro n solution to remain constant, not. considermg possible secoudery reactions. I have discovered that if I pass this current of electricity through water,

made conductive to the electric current for instance acidulated water, and oxids 0 m- -or semipermeable material, and w positive electrode is placed in the chamber contalnlng the oxids of nitro n solution,

thatlthe oxygen produced wil pass to the oxid of nitrogen solution, increasln itiaoxygen content. It is further advisab e in this osite sides process that the pressure on o the same of the separating material shal in order that there shall be no resistance to the free passage of the ions in eachirec-' tion, and also to prevent material diil'usion of the oxids of nitrogen solution into the chamber containing the ne ativeelectrode. By semipermeable material, mean a material, with such pores as to permi'; passage of ions and to some extent of water,

but refusing or making diflicult passage of larger molecules, such as nitric acid. and v uric acid. Such semipermeable material may be unglazed earthenware; if very posul rous it may be made less porous by methods known in the art, such as formin precipitates in the pores. There is no isalvantage that some water passes through the so I sefparating material and enters into the oxids o 1 nitrogen solution; Usually it is of adressure on the water chamber 'a little hig er than 'in the other chamber, thereby passage of oxids of nitron are prevented further. Furthermore, itis necessary that the oxids of nitro n solution contain water. Ifthe solution ii very strong, say less than 5% water, it may be porous 80 to through the. otids of nitrogen to be treated. advisable to add water to the elec- 10o the anodes or the trolysis. the electric current decomposes the water, dilution will not take lace as the result of a moderate addition water, say.v

%. The voltage of the electric current should be highenough to produce oxygen, but not exceed this voltage materially. About 5 volts is found satisfactory, but the voltage may be lower or hi her, and dends on the concentration .0 the solution, its temperature and upon the construction of the apparatus. The strengthof the current depends on the apparatus, time of operation desired, and quantit nitrogen, so that specific in orm-aticn cannot be given.

A high current density is necessa .for roper oxidation wi 1 not take place, while t e current density on the cathode should be quite low, for instance, anode density between three hundred and fifteen hundred amperes per sq. dm. preferthe electrolytic liquid is heatedby the curably one thousand, while the current density on the cathode should be say, between five amperes and one tenth of one ampere. to the sq dm. preferably below one ampere. As

rent, means of cooling should be provided. The temperature. should be below C. or the oxidation may be lessened. Preferabl it should be below 25 (1, but above 109 In the accompanying'drawings apparatus is shown for carrying out my process. In these drawings: Figure 1 is a plan view of one form ofapparatus. Fig. 2 is a vertical section at the same on, line 2'-2,

Fig.1. -Fig. 3 is a vertical section of another form of apparatus. Fig.4 is a rspective view of the negative electrode. Fig-.-

erspetiveview of the, trode s own in Fig. 3.

In Figs. 1 and 2, a is a cylindrical tank, having a central chamber -'b,- the wall. 0 of which is formed of the semipermeable mapositive electerial described. Iii the tank a is placed the oxids of nitrogen" solution to be treated, and in the chamber 6 -is placed acidulated water.- Preferably the tank a is closed;' a stirringal rangement k may. beplaced in tank, a wi-th a view of bringingv fresh untreated solution to the positive electrode. The water is acidified preferably with sulfuric-acid, say 50% by weight. As the s ecific ravity of the oxids of nitrogen so ution is greater than the specific gravity of the water, the wall 0 of the chamber-b is extended above the main tank ato a height Sufficient to give a pressure on that side of the wall 0 equal to the pressure of theoxid of nitro ensolution on the opposite side, or

even a ittle higher pressure. The wall 0 of the chamber 6 should be impermeable to the solutions above the level of the oxids of nitrogen solution so as to prevent the-dilute sulfuric acid from passing through the wall where no counter pressure exists. While the of oxids or 1,ooa,asa

spgcific gravity of the acidified water is only i a ut, say 1.40, the specific gravitysof nitratin g acids containing oxids ofnitrogen is about 1.7 to 1.8. From a suitable source of current supply, electric wires (1 and e are car ried, the wire d leading from the positive pole of the source of current sup ly and the wiree from the negative pole o the source of current supply. The wire d terminates the oxids 0t nitrogen solution and is preferably of platinum. The area of the positive electrode or' anode is governed by a number of amperes used and may, as a rule, be

w merely a coiled platinum wire or other arrangement giving a relativsl small area. The wire e terminates in a cylindrical sheet of lead or aluminum g, a bite may also be used as cathode material in the chamber b. The area used is to be governed by. the current and, as a rule, a coiled sheet is used so as to give a large area. When current is generated, the oxygen ions produced pass through the wall a and increase the oxygen content of the oxide of nitrogen,.transfonning them into nitric acid, while'the hydrogen ions pass into the chamber 6 and ro-' uce no counter-efiect upon the oxids o nitrogen, but escape -from the chamber 5 as hydrogen gas. Platihized platinum has been "found advantageous as anode. material, as -it allows the use ofa low volta e. y The 'tem erature during the electrolysis .should neit erbe too high: nor too low; it may be allowed to raise to say 30. 0., while 10 C.

1n an electrode f in a tank a, extending into is ratherlow for. economical work. .The

" higher temperature causes smaller resistance f to the current and less formation of ersulfuric acid. vBy taking samples from time to time, it' can be determined when all the tiOIl of the vessel i filled with t e ac1du-- lated-water. The electrode 7: in theyoxids Fig.3 the The vessel is of. nitrogen solution and the electrode Z in 4 the acidul .ted water solution are similar to those usedan the apparatus shown in Fig. 1. The ,wire m, leads to .the electrode Z while the ,wire at leads to the electrode in. This wire n ,is insulated where it passes through the acidulated water solution.

. In order to maintain the oxids-of nitrogen solution at the desired temperature, I provide the water jacket 0. Y

p is inlet pipe the water jaclret and u 4 an outlet or dlscharge pi e. Water. or.

other cooling liquid is circu ated b "these pipes "p endg throughthe water ice 'et sur.- rounding the tank. a; i

To prevent or reduce undesirable polari solution and weter, containing an electrobetween' electrodes in the respective high.

tent, which consists in on solutions, the current density on the electrode in the oxids of nitrogen solution being 2. The method of treatin oxids of nitrogen in solution toincrease t eir oxygen con- 21 current of electricity throu h sai of nitro en solution and aci ulated water, between e setrodes in the respective solutions, the curelectricity through sai 3 solution and water, containin rent density on the electrode-in the oxids of nitrogen solution being high. I

-3. The method of treat oxids of nitrogen in solution to increase eir oxygen content, which consists in assin a currentfof oxi s of nitrogen an. electrolyte ,between electrodes in t e respective solutions, the current density on the. electrode in the water being" low.

4. The methodoftreatin oxids of nitro gen in" solution. to eir oxygen content, which; in assing a currentof electricity throu y said Ioxi of nitro 11 solution end aci uljsted water, between ectrodes in the-res ive solutions, thecurrent density on e electrode in the withlated water be low. p

Themeth oitreat" oxids ofnitrogen in. lution toincrease t eir oxygen cona current of electricity through sai 'oxi .of nitrogen solution andwnter, containin an electro ly'te electrodes in t "e respective solutions, the current density on, the elec trodein the onidsof nitrogen solution being above one ,hundredsm' pores-to the .dm. 6. The methodoftreatin oiridso nitrogen in solution to .t eir oxygen content,which.consists in assin a current of electricity through said oxi of nitro solution and sc'i uleted water, between e ectrodes the respective solutions, the current density on. the electrode in the oxids of nitrogen solution being above one hundred to-;thesq.: f oftrea oxidsotnitrcgun in solution increase oxygen electricity through sai oxi ofunitrogkn solution and'water, containing an electro lyte between. electrodesin' the respective solutions, and currentdnsity electror'le. in gg efierb ng elvw n W gen in. solution to increase t eir oxygencon tent, which consists] in assln -a current of electricity through sai oxi 0: nitro 'n tive solutions, the cur solution and acidulated water, between e ec trodes in the res rent density on e ectrode in the wcidulated water being below ten am i 9. The method of treat oxidsiof nitrm gen in solution to increase t eir oxygen col 1- tent, which consistsin ass' .a current of electricity through said foxi of nitrogen solution and. water, containing an electrw lyte between electrodes in the. respective solutions, the current density on theelecs trode in the oxids of nitrogen solution bein g' high, and the current density on the elecf trode inthe water low.-

resto thesqldm'p 10. The method of treating ofni:

trogen in solution to increase their oxygen" content, which consists in a current of electricity through-sai oxids of nitre gen solution and aclduleted watenbetweem electrodes in the respective solutions, the

currentdensit on the electrode in the oxide of nitrogen soutionbeing high and the current density .on the electrode in the widelated water low.

11. The method of oxids. ofnitrogen in solution to increase their oxygen content which in-passing eEcnrrent 0 electricity through, said oxids .of

nitrogen solution and water,- containing an electrol between electrodes'in the respective so utions, the currentfi'density on the electrode .inthe oxids of nitrogen solution beindgnabove one hundred amperes to the sq. .and; the currentdensity ontheielectrode; the water below ten amperes'to the sq. j g

e 12. The method of treatingoxids of trogen in solution to their oxygen conten' which consists in. p

mug. cur. rent o {electricity oxids' ol 7 nitrogen solution I and ecidulated water,

between electrodes in the respective solu tion he" above one hun amperestothefidm 13. The meth .oftreating oxids of ni trogen in. solution to increas'e their oxygen content, which consists inzgassi%e current of electricity through slu ox'i of gen solution and water, contain on -the elecno .trolmqwhile the solutions u u eonnection with eech other'ancl maintaining ture of the oxids of eolution bethe tem ture of the oxide of nitrogen tween 15.C.-a.nd 40C; Y, solution ween 15 C. and 40 C. r In testimony of which invention, I hove 5 trogen in solution to increase their oxygen this 3rd day of September, 1907.

oontent,'whioh consists in 3 our- 7 'rentof electricit throlfgh sa' .oxids ofnitro- V FIN gen solution an acidulated water, while the V solutions are in electrolytic oonneotion with 10 each other, and maintaining'the teg'npera- 14. The method of treating oxids of nihereunto set my hnnd, itlPhilndelphie, on J 

